The treatment of sewage containing organic contaminants has always been a major problem for the industry. Without effective treatment, these organic contaminants cause great harm to human health and the environment.
At present, the commonly used treatment means is “evaporation and concentration+multi-stage distillation”. The sewage containing organics is extracted and separated, the aqueous phase is subjected to evaporation treatment, and the organic phase is subjected to incineration treatment. Evaporation and concentration are not only energy-consuming, but also difficult to process. The stability of the operation is poor. Meanwhile, the incineration of the organic phase not only releases unpleasant odors, causes secondary pollution, but also increases the processing cost.
Accordingly, to solve the above problems, there is also a treatment method of recycling organics. For example, China invention patent with the publication number of CN102040303A uses a pervaporation membrane or a vapor permeation membrane that preferentially permeates organics to separate organics from water in the sewage. The methanol-containing organics is then subjected to steam stripping, and the steamed product is then dehydrated through the pervaporation membrane or the vapor permeation membrane that preferentially permeates water to obtain methanol and derivative products, and the sewage from which organics are removed can be directly discharged into a sewage treatment plant or further processed for use in the production process. Further, Chinese invention patent with the publication number of CN106866412A, uses the water-carrying agent of the acetic acid azeotropic distillation system as the extractant for the PTA-refined sewage, and extracts the organics from the sewage. The extracted phase containing the organic carboxylic acid is returned to the azeotropic distillation column, and then these organic carboxylic acids are withdrawn from the azeotropic distillation column and returned to the PTA oxidation system together with the acetic acid. The raffinate phase is sent to a solvent recovery column and organic solvent is withdrawn from the top of the column to realize the recovery of the organic solvent dissolved in the sewage. However, although these methods recover organic materials, most of them have complicated processes, poor selectivity, and high economic costs.